QUESTIONS IN SCIENCE
What Are Atoms?
Everything around us is made of small particles called atoms. Two or more atoms form a molecule, which is the basis of each substance. For example, a water molecule consists of two atoms of hydrogen and one atom of oxygen. Molecules of a solid substance are held together by a very strong force, so they can only vibrate. The force holding the molecules of a liquid is weaker, and molecules in gases move around freely. It was once thought that the atom was the smallest particle of matter. But scientists later found out that atoms are made of smaller particles called electrons and protons. They each have an electric charge. Electrons have a negative charge and move around a nucleus. Protons have a positive charge and are attached to the nucleus. Some atoms have particles called neutrons which are also tied to the nucleus.
What Makes a Flame
A flame is a bright mixture generated by the combustion (burning) of a substance, either solid, liquid, or gas. For a flame to be generated, there has to be three elements: heat, the combustive (oxygen), and the combustible (some substance that burns). A match bursts into flame when the ‘head’ is at the right temperature for the oxygen to light the sulfur. When we blow on the match, we reduce the temperature and interrupt the combustion.
Why Does Lightning Strike?
Spectacular lightning strikes are caused by short, violent transfers of electric charges, either between two clouds, or between clouds and the Earth. The lower parts of clouds accumulate lots of negative charges -- whilst on the ground, positive electric charges accumulate. When there’s a build-up of negative charges in the sky, these charges start moving toward the positive charges on Earth. This causes lightning. It, in turn, causes a further exchange of positive charges from Earth. Then the negative electric charges jump towards the upper parts of the cloud, which is when we see the lightning flashing.
Why Does a Light Bulb Get Hot?
Light shines from an electric bulb because of the tungsten element inside. The electricity enters the bulb along a filament, goes around the tungsten spiral, and out through another filament. Tungsten is an extremely thin material, so it is hard for the electric current to pass through it. The force needed heats the tungsten to the point where it results in light. And so the bulb gives off both light and heat.